Blade ring and method of producing blade rings



June 27, 1933. G. L. B. WAHLSTEN 11,915,562

BLADE RING AND METHOD OF PRODUCING BLADE RINGS Original Filed June 27, 1929 2 Sheets-Sheet l //V VEA/TOR June 27, 1933- G. B. WAHLSTEN 1,915,562

BLADE RING AND METHOD OF PRODUCING BLADE RINGS Original Filed June 27, 1929 Sheets-Sheet 2 17226 O/ILEHS.

Patented June 27, 1933 time) Lauri Pin greens G6STA LUDVIG BERTIL WAIILSTEN, OF STOCKHOLIVI, SVJEDEN, ASSIGNQR- AKTIE- Bomen'r menses-nears .ANGTUR-BIN, or s'rocxnoma,

GOMEANY SWEDEN, A JOINT-STOCK BLADEQRING- AND METHOD OF ERODUG'ING- BLADE BIDlGS Application filed June 27, 1929, Serial No. 374,226, and in Sweden July 3. 1928. Renewed January 29 1932 p 1 I The present invention relates to blade rings for turbines and has particular reference to blade rings for radial. flow turbines.

The primary object of the invention is to improve the manufacture of such turbine rings, particularly with respect to the manufacture of the root portions of the turbine blades which are attached to blade carrying elements.

In radial flow elasti fluid turbines, as heretofore constructed, two principal methods of manufacturing the blade rings thereof have been employed. The blade rings of such tur-' bines consist of two or more annular blade ca'rrying elements, hereinafter termed ring bonds, between which are situated the turbine blades, the latter being carried at their ends by the ring bonds. In one of the methods heretofore employed, the turbine blades have been cut from lengths of material having the proper section or profile for the blading and these lengths have thenbeen fitted at their ends into corresponding apertures in thin plate ringsythe bladeends being welded to the latter to form a sub-assembly,' the rings of which are provided with projections or grooves of dovetail form adapted to be fitted into complementary grooves or projections in the ring bonds. In accordance 5 7 with the second method heretofore employed,

the blades have been separately manufactured, eachblade being provided at its ends with blade roots adapted. to be connected directly by means of connections of dovetail type the dovetail connection between the blade roots and thering bondsbeing effected by means of a rollingor pressing operation.

The first mentioned method of manufacture has numerous disadvantages among which is the serious disadvantage that the Y welding operation, adversely affects the strength of the materials and causes stresses tending towarp the structure in a manner making it difficult to bring the blade rings to the exact proper form after they have cooled subsequent to the welding operation.

The second mentioned method of manufacture has the serious disadvantage that it is extremely diflicult if not impossible to 59 form the roots of the blades separately to precisely the same shape and dimensions and as a result, the connection of the several blades in any one blade ring, to the rin bonds, will not be uniform. o

In accordance with the present invention I overcome the difiiculties heretofore encoun tered in manufacturing blade rings of the type referred to by assemblinga plurality of blades of the type having roots at their ends into the form of a drum-like structure and with the blades assembled, workin thei blade root-s by suitable operations to a form complementary to the'form of portions of the rlng bonds to which the blades are to be attached and thereafter connectin the rin bonds to the blade roots. D b

For a better understanding of the nature or the lnvention and the manner in which it may be carried into effect, reference may best be had to the following description talc en in con unction with the accompanying draw lugs which illustrate the manner in which the lnvention is employed in the manufacture of several different specific forms of blade rings.

In the drawings Fig. lshowsa cross-section through a part of a radial flow steam turbine having blade r ngs rotating in opposite directions. Fig. 2 shows a section through a part of an embodiment ofsuch a blade ring on a larger scale. Fig. 3 shows a section on line GG in Fire; of a part of a blade ring. Fins. 4 and 5 illustrate the method for the production of such a blade ring in accordance with the present invention. Figs. 6 and 7 illustrate another method ofproduction according, to the invention. Figs. 8 and 9 show sections on the lines A-A and 13-13 in Fig. 6. Figs. lOand .11 show Figs. 7 and 6 seen in the directions of thearrows CC and DD respectively. Figs. 12 and 13 illustrate still another embodiment of a method of producing; a blade ring according to the invention. Fig. 14 shows a section .onthe line -EE in Fig. 12. Fig. 15 shows Fig. 13 seen in the direction of the arrows F-F. Fig. 16 illustrates still afufthel embodi' ment.

In Fig. 1 the dash-dotted line 1 designates the geometrical axis or axis of rotationof the turbine 2, while the dash-dotted line 8 designates a plane about which the turbine is symmetrical. The turbine as shown consists of four blade systems 4, 5, 6 and 7. The

, steam, which enters the turbine through the inlet conduit8, passes the blade systems in named order, between turbine disks 14 carrying the blade systems, and supplies to the turbine energy by means of both pressure and heat losses, every second blade ring in the turbine rotating in a direction opposite to the other.

- Figs. 2 and 3 show a portion of such a blade ring having blades 10 which at each end are connected to the ring connections or bonds l1 and 12 by means of projecting rims 17 and .18 arranged at their roots 15 and16 respectively, which rims are fitted and fixed in complementary slots in the ring bonds in the mannerto be described later on in connection with Fig. 4.

The ring bond 12 is connected in.kn0wn manner to the turbine disk l l by means of a link connection13.

The right-hand part of Fig. 4 illustrates a ,method for producing such a, blade ring.

. The blades 10, which each are .made with 0 thickened block-like blade ends or blade roots 20 touching each other, are'collected to form a drum (or if desired only a part of such a drum), the axis of the drum being parallelito the length of the blades 10, and are held in this position by means of special ,auxiliary devices. According to theproducing method as shown, the blades 10 are assembled on the circular periphery of an interior fitting or mandrel 21 and are laid close together in such a manner that the blade roots, which serve as distance pieces between the blades, are in peripherally abutting relation. Thereupon an outer fitting Q mandrel 22 is placed about the-periphery of the blades thusassembled, forming a drum. or portion thereof. However, in order that the blades with certainty may keeptheir places in correct position in relation to each other during the subsequent working operablades and the fittings.

tion, an easily fused metal is preferably poured through one or several holes 23 in the outer fitting and. solidifies between the By this means the 5:; blades arekept in that position which they endsof the blade roots.

illustrated, this is eifected by turning off shall have in relation to finished blade ring. 7 t

The ends of the blades 20 are thereupon each other in the worked by means of oneor more turning 00 operations to form blade roots of such a shape. that a strong connection is obtained betweentthe blades and the portionsof the ringzbonds complementary in shapeto the In the embodiment lar ringlike projection or rim which, as indicated in the figure,.isthreaded.

The ring bond 12,which is formedwlnl held in a special fitting or chuck 26 (see Flg. 5), for example by turning or by another method, is provided with a peripheral groove 27 which is provided internally with threads complementary to the threads on therim 18. The ring bond 12 is then threaded on the rim formed by the projections on the blade roots. The opposite ends of the blades are treated in like manner to provide a rim consisting of the projections 17, this rim being adapted to be screwed into the complementary threaded groove in the ring bondll. In Fig. 4,'the ring bond 11 is shown in its assembled relationship to the blades.

The threading, or screwing of the ring bonds on to, the blade roots may constitute either the final connection between the parts or may constitute only a preliminary connection. In the latter, case any suitable known method may be employed for effecting final fixing or locking of the ring bonds with respect to the blades. After the ring bonds are screwed to thevblade roots, the easily fused material employed to hold the blades rigidly in position and also the fittings are removed from the blade ring, leavingthe complete blade ring assembly, consistingof the ring bonds having the blades rigidly secured therebetween.

In case the blade ring is of the type employed in the blade system indicated at 6 in Fig. l,consisting of several ring bonds having blades fixed between them, the method is carried out in identical manner, oneof the ring bonds being provided with a second slot 27 opposite to theone shown, in which slot a second blade drum produced in the, same manner as described above is threaded. In this case the easily melted material about the first blade drum may be melted away either immediately after the same peripheral extent than do the projections, as

Wlll be evident from Fig. 9. The slots 27'of the ring bonds 11 and 12 are deepened at 31.

In order to be ableto introduce the lugs 30 in these slots 31 the edge of groove 27 is provided with slots 32 corresponding to the lugs 30, between which slots ridges 33 are formed which correspond'to the spaces between the lugs 30; c I

By this means the ring bonds can be pushed in the longitudinal direction of the blades 10 into the position shown at the left hand side of Fig. 6, whereupon the ring bond and the blade drum are turned in relation to each other a distance corresponding to the peripheral extent of a lug '30 or-ridge 33, so that the lugs 30 will lie behind the ridges 33. It will be evident that the above described construction provides a bayonet type connection between the blade roots and the ring bonds.

In order to insure effective abutting relationship between the parts connected, the lugs 30 and ridges 33 are provided with end faces which are angularly disposed with re production,

spect to the axis of rotation of the ring, as will be seen'in Fig. 11. In order to secure the parts against loosening due to turning relative to each other, some of the means generally known for this purpose are employed, for example by means of clenching the material at a number of places at the bordering faces.

Upon having connected the blades in the above described manner with the ring bonds, the blades are freed of the auxiliary means which is required for keeping them together during the production of the blade roots as well as forthe connection of the blades with the ring bonds.

In Figs. 12-15 there is shown a method of which is to'b'e considered as a combination of both preceding methods- The blades 10 are kept together in the manner above described to form a drum. As shown in Figs. 2-5 the projections 17 and 18 and also the slots 27 are provided with threads which, however, in this case are much larger and in addition preferably have greater pitch. In precisely identical manner as shown in Figs. 611, recesses are made in the projections 17 and 18 and also inthe slots 27, so that'in a like manner as shown in Figs. 6-11, at first the projections 17 and 18 are introduced in the slots 27 and in the longitudinal direction of the blades, whereafter an intimate abutting between the blade roots and the ring bond is obtained by turning the pieces relative to each other a distance which approximately corresponds to the widths of thethreaded ridges.

By this means the blade roots may be fixed to the ring bonds in the manner described in connection with Fig. 2.

The threads provided in the grooves in the ring bonds and on the blade roots need not be continuous threads but-may be of the interrupted type, and instead of threads, an equivalent form of slot or groove may be employed. V

In the embodiment as shown inFig. 16 the blade roots and the ring bond are connected to each other-by means of a dove-tail connection, in which the final connection is obtained in the usual manner by pressing down the rims 34 which previously have had the position as shownat the left hand side in the figure by means of dotted lines. In accordance to the invention the blades are however assembled with their end pieces to form a drum andin this position the blade ends are formed to form blade roots and are given their final form and are connected to the ring bonds.

Many other variations in the method of producing ring connections according to the principle of the invention may be conceived and in the statements above only a few ex amples have been described, by means of which the blade roots may be produced collectively in a simplified manner, and in which the blades are joined to the ring bonds by keeping the blades in proper relation to each other in the positions they have had during the production of the blade roots. By producing a blade ring in this manner, the cosis of manufacture may be considerably reduced without the necessity of employing auxiliary operations such as welding or the like whic-h'have a detrimental and weakening action upon the material. The blades may be produced with relatively little wastage, because the blade roots are manufactured from the beginning in a predetermined position which corresponds to the position they are'to have in the finally completed blade ring structure.

In the several variations of the method hereinabove described, the blade roots have been described as being of a form such that blade roots of adjacent blades abut against each other, the blade roots of a set of blades, when in assembled position, forming a complete annular ring. However, the blades may be made in a form such that the blade roots have less peripheral extent, for example, only so much peripheral extent as may be required to provide the proper strength. In this case, distance piecesmay be arranged between the blade roots, such distance pieces preferably, but not necessarily having projections similar to the projections on the blade roots and adapted to engage theblade rings.

What I claim as new and desire to secure by Letters Patent of the United States of America is:

1. The method of manufacturing blade rings comprising two or more ring bonds and blades provided with blade roots situated between the ring bonds, which consists in assembling said blades to form a drum, working. the roots of the blades to a form complementary to the form of the portions of the ring bonds to which the blades are to be connected and connecting the blade roots, with the ring bonds.

2. The method of manufacturing blade rings comprising a working the blade roots two or more ring bonds and blades provided with blade roots: situated between the'ring bonds which consists i in assembling the blades to formpa drum, to a desired shape permitting attachment of. the ring bonds to the blades by relative turning movement thereof With respect to the" blades, and effecting a preliminary attachment of the ring bonds to the blade roots by turning the ring bonds relative to the blade roots. v p

- The method of manufacturing blade rings comprising two or more ring bonds and blades provided with blade roots situated between the ring bonds which consists in'assembling the blades to form a drum, workingthe blade roots to a desired shape permitting attachment of the ringbonds to the blades by relative '[turning movement thereof with respectto the blades, effecting a preliminary attachment of'the ring bonds to the blade roots bywturning the ring bonds relativeto the blade roots, and subsequently effecting the final locking between the blade roots and the ring-bonds.

4. The-method of-.manufacturing blade rings comprising two or more ring; bonds and blades provided with blade root-s situated between the ring bonds which consists inassemblingthe blades to form a drum, working said blade roots in said ring bonds :to: form cooperating rims or ridges thereon and'effecting connection between said cooperating rims or ridges to' secure the-parts together.

5; The method of manufacturing. blade rings comprising two or more ring bonds and blades provided withyblade roots situated between the ring bonds which consists in assembling the blades .to form a drum, working said blade roots and said ring bonds to form; interrupted cooperating projections thereon, insertin the projections on the blade roots between the projections on the ring bonds and turning the blade roots and the ringbonds relative to each other to bring the projections of the one part behind the projections of the other part '6. The method of manufacturing blad rings comprisingtwo or more ring bonds and blades provided with blade roots situated between the ring bonds which consists in assembling the blades to form a drum,

providing jsaidblade roots and said ring bonds with coinciding ridges and grooves and connecting said blade roots with said ring brands by causing saidgrooves to catch said r1 ges. it v a 1 7. The method of manufacturing'blade rings comprising two or more ring bonds and blades provided with blade roots situated between the ring bonds which consists in assembling the blades to form a drum, providing said blade roots and said rin bonds with coinciding dove-tail-shape ridges and grooves and connecting said blade roots with said ring bonds by causing said grooves to catch said ridges. a

8. The method of manufacturing blade rings comprising two or more ring bonds and blades provided with blade roots situated between the ring bonds which consists in assembling the blades-to form a drum, providing said blade roots and said ring bonds with coinciding dovetail-shaped ridges and grooves and effecting the connection between said blade Ifoots and said ring bonds by attaching the rin bonds and by causing deformation of one o the parts.

9. The method of manufacturing a blade ring of thetype having spaced ring bonds and blades provided with blade roots situated between the ring bonds which consists in pro viding the ring bonds with attaching surfaces, assembling and holding a group of blades in the same position relative to each other which they are to occupy in the completed blade ring, working the blade roots while holding the blades in assembled position to form attaching surfaces adapted to cooperate with the attaching surfaces on the ring bonds and securing the blades to the ring bonds by bringing the attaching surfaces into cooperative attaching relation.

10. The method of manufacturing a blade ring of the type having spaced ring bonds and blades provided with blade roots situated between the ring bonds which consists in providing the ring bonds with undercut attaching surfaces, assembling and holding a group of blades in the same position relative to each other which they are to occupy in the completed blade ring, working the blade roots while holding the blades in assembled position to form complementary undercut surfaces adapted to cooperatewith the first mentioned surfaces and securing the blades to the ring bonds by bringing said undercut surfaces into cooperative attaching relation.

11. The method of manufacturing a blade ring of the type having spaced ring bonds and blades provided with blade roots situated between the ring bonds which consists in providing the ring bonds with attaching surfaces comprising screw threads, assembling and holding a group of blades in the same position relative to each other which they areto occupy in the completed blade ring, working the blade roots while holdingvthe blades in assembled position to provide attaching surfaces i comprising complementary screw threads and securing the blades to the ring bonds by screwing the threaded surfaces together. a a a 12. In the manufacture of blades for radial flow turbines and of the type having enlarged blade roots at their ends, that improvement which consists in assembling and holding the blades in desired position to form a drumlike structure having annular rings at its ends comprising the blade roots, and workingthe ends of the blade roots to provide attaching surf-aces thereon adapted to cooperate with complementary surfaces on blade carrying members common to all of said blades.

13. In the manufacture of blades for radial flow turbines and of the type having enlarged blade roots at their ends, that improvement which consists in assembling and holding the blades in desired position to form a drum-like structure having annular rings at its ends comprising the blade roots, and working the ends of the blade roots to provide surfaces forming a part of a bayonet type goint and adapted to engage complementary surfaces on blade carrying members common to all of said blades.

14:. In the manufacture of blades for radial flow turbines and of the type having enlarged blade roots at their ends, that improvement which consists in assembling and holding the blades in desired position to form a drumlike structure having annular rings at its ends comprising the blade roots, and working the ends of the blade roots to provide threads thereon adapted to be screwed into engagement with complementary threads on blade carrying members common to all of said blades. v

15. In the manufacture of blades for radial flow turbines and of the type having enlarged blade roots at their ends, that improvement which consists in assembling and holding the blades in desired position to form a drum-like structure having annular rings at its ends compr slng the blade roots, and working the ends of the blade roots to provide undercut surfaces adapted to engage complementary surfaces on blade carrying members common to all of the blades.

16. A blade ring for radial flow turbines comprising axially spaced annular ring bonds and blades between said ring bonds, said ring bonds and said blades having cooperating grooves and projections whereby to secure the blade roots to the ring bonds upon turning movement of the blades relative to the ring bonds.

17. A blade ring for radial flow turbines comprising axially spaced annular ring bonds and a plurality of blades between the ring bonds, said blades having roots at their ends and said roots and said ring bonds having cooperating threads for securing the blade roots to the ring bonds.

18. A blade ring for radial flow turbines comprising axially spaced annular ring bonds and a plurality of blades between the ring bonds, said blade roots having erally extending threaded projections and said ring bonds having peripherally extend ing threaded grooves providing a screw connection between the blade roots and the ring bonds.

19. A blade ring for radial flow turbines comprising axially spaced annular ring bonds and a plurality of blades between the ring bonds, said blades having roots at their ends and said roots and said ring bonds hav ing cooperating surfaces providing a bayonet type connection between the ring bonds and the blade roots.

In testimony whereof I affix my signature.

GflSTA LUDVIG BERTIL WAHLSTEN.

periph- 

